As shown in FIG. 9, a conventional probe apparatus includes a probe apparatus main body 1; a mounting table 2, which is movably arranged in the probe apparatus main body 1 to move along X, Y, Z and ⊖ directions and on which an object to be inspected (for example, a wafer W) is mounted; a probe card 3 having probes 3A corresponding to electrode pads formed on the wafer W mounted on the mounting table 2; a clamp mechanism 4 (see FIGS. 10, 11A and 11B) for fixing the probe card 3 with a card holder (not shown); and a test head T electrically connected with the probe card 3 by a connection ring 5. The probe apparatus performs an electrical test on the wafer W by transmitting and receiving test signals between a tester (not shown) and the electrode pads on the wafer W with the test head T, the connection ring 5 and the probe card 3. Further, in FIG. 9, the reference numeral 6 represents a mechanism for enabling alignment between the wafer W and the probe card in cooperation with the mounting table, wherein the reference numerals 6A and 6B represent an upper and a lower camera, respectively. The reference numeral 7 represents a head plate on which the clamp mechanism 4 is fixed.
The clamp mechanism 4 automatically clamps and fixes the probe card 3 transferred by a transfer mechanism. A clamp mechanism of this type is proposed in Japanese Patent Laid-open Application No. H10-189669 (Reference 1). As shown in FIGS. 10 and 11A, for example, the clamp mechanism 4 includes an insertion ring 41 being fixed on a flange portion 1B of a head plate 1A of the probe apparatus main body 1; a lock ring 42 rotatably attached to the bottom surface of the insertion ring 41, wherein the center of the lock ring 42 coincides with the center of the insertion ring 41; and a plurality of, e.g. six, V pulleys 43 for rotatably connecting the lock ring 42 with the insertion ring 41. In FIG. 11A, only one V pulley is shown.
As shown in FIGS. 10 and 11A, the insertion ring 41 includes a flange portion 41A engaged with the flange portion 1B of the head plate 1A; a substantially smooth cylindrical portion 41B vertically and downwardly extended from the inner periphery of the flange portion 41A; and a flange shaped clamp portion 41C horizontally and inwardly extended from the lower end of the cylindrical portion 41B for clamping the lock ring 42 and an engagement flange of the card holder to be described later. At the outer peripheral surface of the cylindrical portion 41B, six circular arc shaped recessed portions 41D are formed at equi-spaced intervals in a circumferential direction, and one V pulley 43 is rotatably arranged at each recessed portion 41D. The clamp portion 41C serves as a reference surface when fixing the probe card 3.
The lock ring 42 is formed to have an inner diameter allowing the cylindrical portion 41B of the insertion ring 41 to be inserted into the lock ring 42 with sufficient clearance. As shown in FIG. 11A, the lock ring 42 includes an upper ring 42A engaged with the radially inner part of the flange portion 41A of the insertion ring 41; and a lower ring 42C combined with the upper ring 42A by means of a force of springs (not shown) with a plurality of (e.g., four) joint pins 42B. Also, the lock ring 42 rotates clockwise and counterclockwise by two air cylinders (not shown). The inner diameter of the upper ring 42A is greater than that of the lower ring 42C, and the inner diameter of the lower ring 42C is greater than the outer diameter of the cylindrical portion 41B of the insertion ring 41. A V groove 42D, into which the six V pulleys 43 are inserted, is formed along the entire circumference of the inner peripheral surface of the upper ring 42A to allow the lock ring 42 to be freely rotatable with the V pulleys 43. In addition, the reference numeral 42F represents a cam follower for supporting the card holder.
As shown in FIGS. 11A and 11B, each V pulley 43 includes a bearing nut 43A attached to the top surface of the insertion ring 41; a bearing pin 43B screwed into the bearing nut 43A from the lower side of the insertion ring 41; a pulley 43C rotatably supported by the bearing pin 43B; and a spacer 43D for adjusting the height of the pulley 43C. Further, as shown in the same drawings, an axis 43E being inserted into the hole of the insertion ring 41 is formed at the center of the bearing nut 43A, and a female screw portion 43F, into which the bearing pin 43B is screwed, is formed at a slightly eccentric position with respect to the center of the axis of the bearing nut 43A. Because the center of the axis of each bearing pin 43B is eccentric with respect to the center of the axis of corresponding bearing nut 43A, by rotating the bearing nuts 43A after attaching the V pulleys 43 to the insertion ring 41, the pulleys 43C can be engaged with the V groove of the inner peripheral surface of the lock ring 42 and the lock ring 42 can be combined with the insertion ring 41, or the engagement can be released and the lock ring 42 can be detached from the insertion ring 41.
In other words, when attaching the lock ring 42 to the insertion ring 41, the height of each V pulley 43 is adjusted by the spacer 43D, and the horizontal position of the lock ring 42 is adjusted by the directions of the bearing nuts 43A, so that the center of the axis of the lock ring 42 can coincide with the center of the axis of the insertion ring 41.
Further, a test head having a bearing mechanism for adjusting a connection state of the test head and a probe card is proposed in Japanese Patent Laid-open Application No. H8-102477 (Reference 2). The bearing mechanism has a test head main body and a support frame thereof. The test head main body is supported by bearings arranged at four corners of the support frame and capable of rotating horizontally in the support frame. Vertical and horizontal bearings of the bearing mechanism are rotatably attached to each attaching block. The horizontal position of the test head main body is regulated by the horizontal bearings and a vertical side of a guide block, and vertical position thereof is regulated by the vertical bearings and an upper and a lower guide block.
However, the probe card clamp mechanism of Reference 1 has some drawbacks as follows. First, the structure of the clamp mechanism is complex because the lock ring 42 is configured with a plurality of members such as the upper ring 42A, the lower ring 42B and so on. Further, both of the height and the horizontal position of the lock ring 42 with respect to the insertion ring 41 need to be adjusted by using the V pulleys 43 for attaching the lock ring 42 to the insertion ring 41. Moreover, it takes a long time to adjust the position of the lock ring 42 in the X, Y, and Z directions because the plural V pulleys 43 are arranged along the peripheral direction of the insertion ring 41 and the lock ring 42. Further, the test head of Reference 2 is not for a clamp mechanism, but for adjusting the connection state between the test head main body and the probe card. Thus, its mechanical structure is totally different from that of a clamp mechanism.